Well logging method and apparatus



June 2, 1953 F. G. BOUCHER WELL LOGGING METHOD AND APPARATUS 5Sheets-Sheet 1 Filed April 2'7, 1948 ULLEY iDaTacTok.

5 4 G We Q 2 N G m T mc NE, T E 4. W5 k Frank. G. bauclzer' sax/amberJune 2, 1953 F. G. BOUCHER WELL LOGGING METHOD AND APPARATUS Filed Aprii27, 1948 5 Sheets-Sheet 2 M/QBMSM June 2, 1953 F. G. BOUCHER 2,640,271

WELL LOGGING METHOD AND APPARATUS Filed April 27, 1948 5 Sheets-Sheet 31: ranIL Qboucher' Savanna? Cltborneg 1 June 2, 1953 F. G. BoucHER2,640,271

WELL LOGGING METHOD AND APPARATUS Filed April 27, 1948 5 Sheets-Sheet 4Frank. G. boucher" Boa/eaterb3 .{2 W Clbtoraeg June 2, 1953 F. s.BOUCHER 2,640,271

WELL LOGGING METHOD AND APPARATUS Filed April 2'7, 1948 2 5 Sheets-Sheet5 FI6.-IO

Frank: Qboudher \BQVQOLOI' CLLLornex Patented June 2, 1953 UNITED STATESWELL LOGGING METHOD ANDAPPARATUS Frank G; Boucher, Tulsa, Okla.,assignor to.

rant rice Standard Oil Development Company, a corporationof DelawareApplication April 27, 1948, Serial No; 23,490

8' Claims.

from a particular locality, it is neverthelessnecessary to. actuallydrill. fortheoil in order to" ascertain whether or not oil is actually.present. The drilling in the-earth of a suitableborehole, or well; totest for oil is an exceedingly expensiveprocedure. Consequently, toobtain theimost benefit from such drilling operation, every effort ismade to obtain. as muchinformation as possiblef rom the drilling of eachwell. This is done-in order to eliminate the possibility" of overlookingpossible producingstratain the well while it isbeing bored, and also to.obtain information to the structureof the earth, which. will lead toestablishing the presence of. oil in an adjacent V locality or moredeeply in the wellbeing drilled. Gonsequently, extensive methodshavebeen developed for examining a bore hole to determine every particle ofinformationthattcan be obtained as to the nature of strata through whichthe well passes: These methods are called well logging methods, andgenerally comprise methods for preparing continuous plots of thephysical or chemicalcharacteristics 0f the well along its entime length.it isthe primary purpose of this invention toprovidea: new well loggingmethod for determining information from-a borehole-astotherelativehardhessand the exact orientation of strata adj aoent thebore hole.

Theorientation of a stratum is ordinarily indioatedby angles of dip?and-the directionof strike-f The-angle of dip is-defined to he the angleof inclination of the plane of stratification with ahorizontal plane,while the direction of strike is defined tobethe direction of" the lineofintersection-of" the plane of stratification and a horizontal plane.Having obtainedthe dip and strilre of a particular stratum; it isapparent, therefore, that the exact orientation:- of. thestratumahasbeenestablished; This information is useful .inzpredictingthepossibility of obtaining oil iir the bore" holetested,. inestablishing the general geologic nature of the adjacent earth,- and.for' the Y indication of. possible-nearbyoil' deposits.

It has been discovered that-the dip andstrike.

of strata through which a bore hole passes may. be determined bycorrelating information readily obtainable by suitable apparatus. Abasioprin'rcipleon. which the operation of this apparatus works is'that"the diameter ofa bore holevariesi somewhat proportionately to thehardness-of the strata through which the bore hole passes. Thus as thebore hole passes through an extremely hard formation, the diameter ofthe bore hole.

will be somewhatless than it is in passingthrough a: soft, orporousformation. The difference. in. the diameter of the borehole, inrelationto dif ferent types of stratais due to several factors.

Onefactor is that the drilling tool will tend-to.-

brealz off, or cut, a somewhat larger. hole in a soft formation. than.in a hard formation. Another factor is that due to. the-conventionalcon-- tinued circulation of drilling mud, or. a similar. fluidduringdrilling operations. preferential. erosion-10f.- softer stratawill-occur. In any event it is now established that. theprincipleindicated aboveis correct.

The basic. principle, therefore, that the diameter ofa bore holeat aparticular point is a. function of. the hardness of. the strata at'thatpoint, provides a. suitable means forobtaining therelative hardness andthe dip and strike of strata in the bore hole. Thus. if. a measuring-ldevice is passed through the. bore hole to accurately determine the.diameter of the bore hole along the length of the. borehole,.it.is,.possihl'e to identify the harder and. softer strata.through which the bore holepasses. If. this same. typeof measuringdev-iceis modified soas to maintain .the device in essentially acentral. position. at. all. times, and if a. plurality of measuring.devices arranged in a-horizontalplane are used to measure the variationin the distance-of. thebore hole from the central partofthe bore hole,it ispossible to-determine the inclination. of harder. soft strata atparticular points in. the bore hole. For example, if a measuring deviceisimaginedhavingtwoealipers, the contactpoints of. these calipers beingvina horizontal-plane, and ifit isassumed-the measuring deviceismaintained at the center of abore hole, as it is moved downwardly, themovement inwardly of. one. caliper, due to. a decrease in the diameterof the bore hole before the-other caliper moves inwardly will-indicatethat-the plane of stratificationis inclined so that the. point ofcontactof the first caliper is above that of the secondcaliper. It is apparentthat-in addition to this information it is necessary to time aparticular measurement ismade; andthe vertical difference in heightbetween the inward movement of the calipers. In other words in theexample just given, if the azimuthal direction of the calipers be known,then the angle the particular stratum deviates from horizontal in thisdirection will be the angle having a tangent equal to the verticaldistance between contact of each caliper with the particular stratumdivided b the diameter of the bore hole. It is apparent that thisinformation will only give the inclination of the stratum in theazimuthal direction the two calipers are oriented in, so that it isnecessary to employ three or more calipers to actually ascertain the dipand strike of the stratum. However, the principles set forth above arethe basic principles involved which will permit a full understanding ofthe apparatus of this invention.

In accordance with these principles, therefore, a preferred embodimentof this invention comprises the following components: Three or more, andpreferably four. caliper measuring devices are provided, together withcentering and guiding means to maintain the apparatus in substantiallythe center of a bore hole and to maintain the apparatus in alignmentwith the bore hole. As an integral part of this apparatus an orientingdevice is provided which will determine the azimuthal orientation of theapparatus and also an inclination detector is incorporated to determinethe inclination of the apparatus from the vertical in the event the borehole is not vertical. This entire apparatus is then lowered down a borehole employing a cable together with a suitable measuring device todetermine the depth of the apparatus in the bore hole. The cable alsoincludes electrical conductors connected to the calipers, an orientindevice, and an inclination device so as to permit recording on thesurface of the earth of all necessary information to precisely indicatethe dip and strike of strata traversing the bore hole.

.In the accompanying drawings a preferred form of the apparatus of thisinvention is indicated. It is apparent that this apparatus is adaptableto many modifications and refinements. It is to be understood,therefore, that the scope of the present invention is not to be limitedto the embodiment illustrated.

In these drawings:

Figures 1 and 2 diagrammatically indicate the entire apparatus; Figure 2comprising the lower continuation of Figure 1. These figures generallyindicate the arrangement of the different components and particularlyshow suitable centering and caliper devices.

Figure 3 shows the general configuration of strata adjacent a bore holedown which the apparatus is to be lowered.

Figures 4, 5, 6, and 7 show a suitable inclinometer for use in theapparatus of Figures 1 and 2, Figure 4 being an elevation, partly insection, of the device; Figure 5 being a view taken along the line VV ofFigure 4; Figure 6 being a fragmentary view showing an alternativemethod for mounting the pendulum of the device; and Figure '7 showing atop view of the shutter with which the device of Figure 4 is provided.

Figures 8 and 9 illustrate a suitable orientation device for use in theapparatus of Figures 1 and 2, Figure 8 being an elevation partly insection of the device, and Figure 9 being a view of Figure 8 along theline IX-IX.

' Figure 10 diagrammatically shows a suitable electrical circuit forconverting the movements 4 of the calipers of the apparatus of Figures 1and 2 into electrical energy to permit recording.

Figures 11 and 12, similarly to Figure 10, show somewhat differentcircuits for the same purpose, each making it possible to obtain arecord of the movement of the calipers of Figures 1 and 2.

Figure 13 in a fragmentary diagrammatic view shows a modification of thecaliper arrangement of Figures 1 and 2, providing a different means forconverting the movements of the calipers into electrical energy.

And finally, Figure 14 shows the type of record obtained, indicating therelative hardness, the dip, and the strike of strata traversing a borehole down which the apparatus is lowered.

Referring now to Figures 1 and 2, the general nature of the entireapparatus of this invention is illustrated. The apparatus comprises thecasing I, containing an orientation detector and an inclinationdetector, the centering device 3, the measuring device 4, and thecentering device 5. All these units are suitably sustained in a borehole by means of cable 2, which includes con.- ductors to the differentparts of the apparatus as will be described. The centering devices 3 and5, which are similar to each other, the parts of which are identified bysimilar numerals, serve to maintain the entire apparatus in essentiallya central position in the bore hole. This is accomplished by virtue ofthe spring elements 6 which contact the sides of the bore hole. Whilethe drawing simply illustrates two leaf springs, 6, on each of the twocentering devices, it is preferred to use at least four leaf springs forthis purpose. These springs are fixed to bearings I which slidablyencircle a shaft 8 provided with shoulders 5. Consequently, as theapparatus is lowered down a bore hole, contact of the leaf springs 6with the bore hole causes an inward compression of the spring membersforcing the bearings 1' along the shaft 8 within the limits provided bythe shoulders 9. By the nature of these centering devices, a reducedcross section or an expanded cross section in the diameter of the borehole will equally compress or equally relieve each of the spring members6 so as to maintain the entire apparatus, at all times, essentially inthe center of the bore hole and in alignment with the bore hole. Thespring centering devices also perform the function of minimizingrotation of the apparatus in the bore hole as the apparatus is lowereddown the bore hole. Furthermore, the tension of the springs 6, againstthe sides of the bore hole is sufficiently great at all times so thatthe position of the apparatus in the bore hole will not be affected bycontact of the calipers 62 with the bore hole. Thus, for example,contact of only one of several calipers against an isolated projectionof the bore hole will not cause the apparatus to move, preventing thereceipt of false signals from the other calipers. It is apparent thateach of the functions of the centering devices indicated is necessary inorder to obtain proper information from the orientation detector, theinclination detector, and the calipers. The bore hole diameter measuringdevices employed in the apparatus of Figures 1 and 2 comprise a,plurality of calipers, generally indicated by the numeral 4. Again whiletwo of the caliper arrangements are illustrated in the drawing, it ispreferred that four be employed although three would be sufficient andany greater number could be used. Each of the calipers comprises twoarms 62 which are pivoted this fragmentary view of the calipers and case63 which supports the calipers, the variable inductance coil 67 isreplaced by the variable resistance 91. This resistance 91 is suitablysupported on the casing 63 by the rod 98 which is insulated from thecasing by insulation 9!. This rod may be provided with a terminal towhich conductor 93 is connected. The contact 95 of the resistor 91 issupported and pivoted by rod 90 so that the contact can move along theresistor 91. Rod 90 is fixed to the casing 63 through insulation 9| toconnect to conductor 9 1. The movements of contact 95 are controlled bythe non-conductive rod 96 which is coupled to the caliper. Thus,movements of the caliper cause contact 95 to move along resistor 97varying the resistance across the conductors 93 and 94. By placing abattery and a recording galvanometer in a circuit with conductors 93 and94, a record may be obtained of the movements of the calipers. While notshown in Figure 13 it is preferable to position a liquid tight housingaround the resistance 97 and contact 95. This may readily be done byproviding a packed opening in the housing for the rod 96.

As indicated above, therefore, there are numerous methods of convertingthe movements of the calipers in apparatus embodying this invention intorecordable energy. Thus, as indicated, the calipers may vary theinductance of a coil or the resistance of a coil or the calipers mayvary the resistance of a non-inductive resistance. Still furtherexpedients which may be used are to employ Selsyn systems, hydraulicfollower systems, or piezoelectric apparatus. It is clear, therefore,that this invention is not to be limited to any particular method forobtaining a record of the caliper movements.

Having now fully described the manner of supporting and positioningsuitable devices for o taining profiles of the bore hole, the way inwhich this can be used to determine the dip and strike of strataadjacent the bore hole may be appreciated.

Illustrated in Figure 3 is a typical cross section of a bore hole 99showing the variation of the profile of the hole due to strata ofdifierent hardness. Thus since strata I and I Ill are harder than strataI62 and I03, these strata cause a reduced cross section of the borehole. Furthermore different strata may have some degree of hardness, butwill slough off at difierent rates due to different characteristics,thus resulting in different cross sections of bore hole. At theintersection of the bore hole and the particular hard stratum therefore,a projection exists relative to the adjacent softer strata. Due to theincline of the strata, these projections are not in the same horizontalplane. Consequently, if the caliper device described is lowered downthis bore hole, the calipers will not simultaneously strike the hardstrata I00 or IOI but will strike the strata in a sequence dependent onthe incline of the strata. As this sequence may be determined from therecords of the caliper movements, the incline of the strata may readilybe obtained relative to the calipers or the case supporting thecalipers. However, two further complications must be met to determinefrom this the dip and strike of the strata. First it is necessary todetermine the orientation of each caliper with respect to the directionsof the compass, and secondly it is necessary to determine theinclination of the apparatus supporting the calipers. It is necessary toobtain the orientation of the calipers since there is probably no way ofpractically lowering the apparatus down a bore hole in a fixedorientation. While the centering devices described minimize rotation ofthe apparatus, nevertheless, irregularities in the bore hole andtorsional forces due to the unrolling of the supporting cable at thesurface of the earth do cause periodic or continued rotation of theapparatus. It is also necessary to determine the inclination of theapparatus since there is probably no way of practically maintainingsuitable apparatus in a truly vertical posi tion. Thus in the embodimentdescribed, as the apparatus is aligned with the borehole, any departureof the borehole from vertical will incline the apparatus. As boreholesare often notoriously non-vertical it is apparent that a suitableinclination detector is a critical part of this invention. These tworemaining components of this invention, the inclination detector and theorientation detector are indicated generally by numerals I64 and W5 ofFigure l and will now be described in detail.

A suitable form of inclination detector is indicated in Figures 4, 5, 6,and '7. Referring now to these figures, it will be seen that mountedWithin a casing II, which in turn is mounted in the case I of Figure lis a circular shutter I2, arranged for rotation in the casing H with theplane of the shutter at right angles to the longitudinal axis of thecasing. A suitable means for supporting the shutter for rotary motion isa ring shaped track 83 secured to the casing II at its periphery andprovided with ball bearings I4. A downwardly extending circular ledge I5secured to the underside of the shutter completes the supporting means.A ring gear I5 is secured to the peripher of the shutter and arranged torotate the shutter actuated by a motor Ii having a vertically extendingshaft I8 provided with a gear I9 arranged to cooperate with the ringgear of the shutter so as to rotate the shutter at a constant speed.

Mounted in the casing below the shutter is a pendulum mounted for freemotion in all directions. Attached to the upper extension of thependulum is an optical tube 2I in which is arranged a light source suchas a globe 22 and a lens 23. The light source, lens, and optical tube,are arranged to produce a beam of light having rays parallel to thelongitudinal axis of casing I I and the casing I when the casings areperpendicular. From the above description it will be apparent that whenthe casing is perpendicular the beam of light from the optical tube willimpinge on the center of shutter I2.

In the embodiment illustrated in Figures 4 and 5, the pendulum 20 ismounted on gimbals 25 and power for operating lamp 22 is transmittedthereto through the gimbal ring by means of conductors 25 andcommutators 26 as appears in the drawing. A cable 27 is providedextending from cable 2 of Figure 1 to transmit power down through thecable, through conductors 28, for operating both motor I I and lamp 22.

Mounted in casing II in the upper end thereof, above shutter I2, is alight sensitive means. A satisfactory arrangement is that shown in thedrawing comprising a pair of photocells 29 and 30 together with aconcave mirror 3I mounted above the photocells. It will be evident thatthe arrangement of photocells and the mirror is such that any lighttransmitted from lamp 22 through shutter I2 will be efiective to actuateeither photocell 29 or photocell 30. The signal received by the pair of.photocells 2,9 and. 3. 1 istrag smittegi through conductors 32 and "33to the amplifier diagrammatically indicated. by rectangle The amplifiedsignal is then transmitted throughithe insulatedoonductors 35 containedwithin cafole 2? and cable 2 to a recording galvanometer not shown,rangeri at ,th rface of the earth.

A top VlSW of a suit-a shutter for to d vice is shown in Figure '5. El.portientfi J from the shutter sothat when the 9513a II is verticallittle or no light .Will be passe Joy shutter l2 from source 22 t;ph0tocel1s ,29 ":1 36. Howevenupon deviation of easing [1,. the vertical,light will betransmitted frQmwt e lamp to the photocells with eachrotation oithe shutter. The opening 36in the shutter is. so ar-- rangedthat-With increasing. displacement of the axis of casing H fromthevertical, there is a progressively increased time oi-exposure thephotocells to light from the other words, when the casing! l leviatesfrornthe vertical a pulse .is transmitted by the photocells witheach-revolution of theshutter, the di i '.a tion of the pulses being aiunctionoi the..(ieviation of the casing from-the vertioal. alibratingthe pulse length with respectvto incl-ination, the exact inclination canhe dietermined.

A modi-iication of the-:meansior suspeneling the penduluin isillustrated inFi ulfe. 6. In this embodiment a call M is attached to thependulum and a member 55 adapted to,ce. seci1re. it0 .the casing definesa suitable; socket to cooperate .v;ith the ball. .In this embodimentleadvziresiit connect 1a-mp'22 to the source of sewer. The'lead- Wiresare of ample lengthtoallow. the -pendulum to move freely, in alldirections. Theremaincier ofthe apparatus according to this-modificationmaybe the samev asin Fieure ten accordingly is not again illustrated.,The typeof, record produced by the in01inome erand the in erpretation I.01 this record will he discussed hereinafter connection with Figure 14of the drawings.

Referring now specifically to Figures .s ar ci 9, .asuitable orientationdetector -.to he: contained in casing l of Figure 1; is indicated. The,detectorhas a shell or case 4|, eta, non-magnetic material suchasbrass, havinemounted t ereine circular-member $2,.to which is.. attacleci bar magnet 43. Apivot M extends th fqligh nemlger 42; and issupported ty.a..suitabl brack W- Al annulusfiihasits p ripherysecuresitoica e M and is arranged. so tha t c rcl defi ed :byit inner.eircumferens- .is sli tly. ab ve and insid fthe periphery of :member.52- Membe -45 .is providedwith anopeninew l inand membe Y $2 isprovided. withasnni arbut ma le -openin 4i. Opening. 66. is preferablyin..-line-virit pivo :point ikand:oneaoithehamper ;,1 \W. mop- :parentmatstheiarraneement i st 1d. .e -ois :generally similar t0;a marmecompass, wit nsen- :ing llficorresponding .to the lubbersiilwnn 5.941111compass, and opening til correspondin motil north point of the compass.

Some clistanoeaboveimemberz$2- a mqtwi oi sse uredto-byacketiiQ,withghaftfifl-oflih 1 19159 sle-teralignedwith thepivot Mofmember- 4:2. v ally-extending member I :isisecuredito :shafiiil-and--carried thereby ;is prism ;:52.. xAsenr-ce-mf light; 531315stationarily arranged atl-iasentmri m :..52 ,:so.;that. each-rotationofthe prismia l gh from source .52 white transmitted through-open-..iings- 46am 4 As wilibewealtisnemssar Lita synchronize the r tationofthe yprismifiz with the rotationoftheshtflter: J. .0..the inclinatiodetector. may ..be .olone hy..iisipg .contant s eegLmgt rs f or bothcletectors adapted to rotate the shutter and prism at the same speedl Altemativei .s nei eonsiamspeeil; motor m x-ts emp oye i917 drivin .boih tsh t a mhis c s it onr ei t nq' iw the moto in th ca e of the o i gvice, emplo ng su ta searing npqn eq n w h? shat-te t d sueward memeiifin eec or tori th rinaeea s e ene th samerp a iopal s eedeiheiirismwrite it. i eee sa to s nchro ze erqietien'q "th tereml-thesris e ..ihetw e e tqr M els insrwh-a a that themeqil 'P. fiprise snt.awav.rz9ti q g the shiiiierl sf. passin tlmquellthe pr sm andthe nter of rotation of the. rism, B y thi meansit i spos- .Sible tocorrelat machetei incli ation wit the orie tate o ithe appa a uses to..i lir ctioeef ncline eswil be ap aren inthis description.

Below members a d .45 isfise suitabl curved mirror .5 ,Tl3h ...m .r orres..t 1.e to: g t ransmittedthrel sh. Qpe es'A an .1. 29 au emral arraed. l g sen .1... asuitablelight sensitive dev ce a Photo cell .55 maybe, employed and is cliagran rn W lustrat d in th id flw negwith the...celkiee pie o th amp fie diagrammat call ind c s E21 for supp yinepower.o melifie rfifii. eet rliiisehd li ht sou ce 573 n asis ioninesisrieDlifl 56 may b t ans it ed to th ee rate. em r i mepri mtz asses aheveo.rfii' ie 14.6 a ray o iiehi wiil. harassed throush s, om

: E 1 h, ...ori.e l .a.tiq -iw lhe ind qateciihy hee eiilarsgphoiAiQirQfreblY' lie anines .maemficma efiaL v thr ugh cas shoulclrb sh l d cing and ,e refiectedto light sens means 455- .Inlikemanne the pass ge.QllB lemmingwi lzeausea ayoi 'ghtt b .iariiy transmi t d-to the 11gbiiive. lstu lq 55. Whenep mngs rad ustm -1. sht..fro.mcsourq -,3 wi e.sn vl aoemovemettpime rib ri? pee to eas ng) g .Y deviation .of

.. imilr The. nature o .a sui ab e mbodiment (sf-this invention havingnow; been" fully 'descr-ibed,=-the record apdthe interpretationof'therecorel-proguged pyth integral apparatus'maynowbeeonsidered.

Illustrated, in Eigure- 14 is diagrammatically indicated} typical recordobtainable @withethe tor is indicated by line H6 of Figure 14. formerlyindicated, the length of the pulse ll'l indicates the degree ofinclination.

well logger of this invention. The record shown may be produced on astrip of photographic film H showing the fluctuations of galvanometerscontrolled by the calipers, orientation detector, and inclinationdetector. In addition to these records, a record should be made of thedepth of the apparatus in the borehole. Suitable devices for indicatingthe depth of a cable suspended tool are well known to the art and sowill not be described. The markings produced by a suitable depthindicator are represented by line HI of Figure 14. 'The notches H2 ofthis line periodically appear to indicate distances on the record papercorresponding to a given distance in the well. For example a notch H2will appear each ten feet the apparatus is lowered.

The line I 13 on this record represents the type of record produced bythe orientation detector described. The passage of light through theopening 46 of the detector is shown by the kicks designated by numeralH4. Similarly the passage of light through the opening A? is shown bykicks H5. Since the larger opening 45 allows a greater amount of lightto pass than opening 47, the kick produced by passage of light throughopening 43 may readily be distinguished. It will be recalled that if thekicks I I4 and l 15 coincided, it would indicate that opening 46 wasdirectly north of the center of the apparatus. However, since the kicksHd fall approximately midway between the kicks H5, it is apparentopening $5 is almost due south of the center of the case. An actualrecord of course can be accurately examined to obtain the bearingprecisely. Assuming, as stated to be preferred, that one of the fourcaliper arms is aligned with the opening and the center of the case, theexact orientation of this caliper is now known. Similarly the positionof each of the other calipers is also known. For example if the fourcalipers are symmetrically placed around their supporting case, then itwill be known that one caliper, as indicated .above, is pointed duesouth and that the other calipers are pointed east, north, and west.

The record produced by the inclination detec- Thus the fairly long pulseIll indicates an inclination of approximately 10 degrees. As therotation of the shutter producing the ulse is synchronized with therotation of the prism in the orientation device, the occurrence of thepulse H! at the same time as the kick H4 due to light passage throughopening 46 indicates the apparatus is inclined in a plane assing throughopening 45. As opening 46 was found to bear due south of the center ofthe apparatus, the apparatus is positioned so that the intersection ofthe center line of the apparatus, at the bottom of the apparatusestablishes an angle of 10 degrees with a vertical rererence line, theplane established by these lines being due north and south. Thus thedirection of incline of the apparatus may readily be round by extendingthe median point of pulse i ll to line H3 from which the direction ofinclination can be read. It must be understood, however, that thisprocedure is only valid if the preferred protor. If not, so long as bothshutter and prism rotate at the same rotational speed, the relation ofthe time of pulse H1 and the pulse H4 may point of pulse H7 appears.

been calibrated to show this.

be determined just prior to lowering the apparatus into the ground,after the constant speed motors have been started. In other words solong as the constant speed motors of the inclinometer and orientationdevice are rotating at the same speed, there will be a fixed angularrelationship between the shutter 01 the inclinometer and the prism ofthe orientation device. In the preferred procedure the angularrelationship is zero, the shutter and prism rotating together.Consequently in this case the direction of orientation will be thedirection of orientation of the opening 46 of the orientation deviceplus the number of degrees beyond which the median This may readily beobtained from the record of Figure 14. Alternatively either before orafter the apparatus is placed in the borehole, it may be inclined in aparticular direction, for example north, to obtain the angularrelationship between the prism and shutter. In this case the directionof inclination will be equal to the orientation of opening 46 at anyinstant plus the angular relationship between the prism and shutter plusthe number of degrees beyond this point at which the median point ofpulse HI appears. These points may readily be determined by dividinglines H3 and l l6 into degrees. This can be done by noting that thedistance between pulses H4 will be equal to 360.

Having now established from the record of Figure 14, the depth of theapparatus, the orientation of the calipers, and the inclination of theapparatus, it remains only to interpret the records of the calipersindicated by lines H9, i2fl, l2l, and I22. These lines represent aprofile of the borehole traced by each of the four calipers. If it beconsidered that the calipers are numbered I, 2, 3 and 4 around the case,then line H9 may represent the record of caliper 5, line 29 that ofcaliper 2, line l2l that of caliper A, and line 122 that of caliper 3.It will be noted on the record that three strata are indicated by thecalipers. Due to the sequence in which the calipers touched the strata,it appears the uppermost stratum indicated by traces I23 is sharplyinclined from caliper 3 down to caliper l. The stratum indicated bytraces I24 is inclined in the same direction but not as steeply, whilethe stratum indicated by traces I25 is in the same plane as the fourcalipers. It must be remembered of course that the inclination of thecase must be accounted for in determining the actual incline of eachstratum. Thus the stratum indicated by traces I25 is not horizontal butlies in the plane through the calipers determined by the inclination ofthe apparatus as formerly found.

In accurately determining the dip and strike of strata from a recordsuch as that shown, the following principles may be employed. It isgenerally most convenient to first neglect the inclination of theapparatus and to find the incline of each stratum assuming the apparatusis vertical. When this has been done, by rotating the established planein accordance with the inclination of the apparatus, the actualorientation of the particular stratum may be found. In carrying thisout, the vertical distance between contact of each caliper with aparticular stratum may be found by referring to the depth markings shownby the first line on the record. The distance of each caliper from thecenter of the case may be found provided the record has Thus verticalreference lines may be drawn on the record adjavenient manner ofdetermining the orientation "of each stratum is'to employ a suitablemodel. The'model may consist of 'two planes having adjustableelevations. The lower plane may be elevated to an inclinationrepresenting the plane which the'caliper arms lie as dictated by theinclination of the apparatus.

The upper plane may then be elevated proportional to thevertical'diiference'in height between contact of the Calipers with theparticular stratum, having the supporting points of 'the plane separatedjust asthe 'calipers are. This will then establish the upper .plane inthe exact orientation of the actual stratum permitting measurements ofthe dip and strike of the stratum from this model.

'As-de'scribed, therefore, the present invention comprises the methodand apparatus for obtaining the dip and strike ofs-trataadiacent aborehole. The procedure entails lowering a properly centered and alignedmeasuring device down a borehole, having means for obtaining at leastthree profiles of the borehole and for obtaining the azimuthalorientation and the inclination of the apparatus while profiling. Theapparatus employed preferably comprises four caliper profiling meansarranged between two centering and aligning means. Any suitable type oforientation and inclination detectors may be em ployed.

The information thus obtained enables determination of the exact path ororientation of the borehole in the earth, the relative hardness ofstrata adjacent the borehole, and the dip and strike of strata adjacentthe borehole. All of this information may be obtained with a high degreeof precision by means of the method and apparatus described.

As the present invention is capable of many embodiments, modifications,and substitution of equivalents it is to be understood the appendedclaims should be given a broad interpretation commensurate with the truecontribution to the art.

I claim:

1. Well logging apparatus comprising, in combination, a body adapted tobe lowered into a bore hole, at least three profiling arms movably heldby said body and equally spaced circumferentially about said body, meansurging each of said profiling arms independently outwardly from saidbody, means adapted to measure the independent movement of each of saidprofiling arms relative to said body, a first centering means positionedon said body above said profiling arms, a second centering meanspositioned on said body below said profiling arms, said first and secondcentering means acting to center said body in the bore hole and to alignthe body with the bore hole, azimuthal orientation means and inclinationmeasuring means positioned in said body, and recording means associatedwith said profiling arms, said azimuthal orientation means and saidinclination measuring means to record simultaneously indiciarepresentative of the independent movement of each of said arms, theazimuthal orientation of a selected point on thebo'dy and the'ir-iclinationxr'of :the body from the vertical.

2.' A;pparatus according -.to fclaim'l in which said body is providedwith circumferentialiy spaced vertical slots, and in which eachnof :said

tached to the inner #ends of each segment and slidably fitted withinsaid vertical slots.

3. Apparatus according to claim 1 in which the means adapted tomeasurethe independent movement of each of the" profiling arms relative to-thebodyi'ncludes a coil heldbysaid body and an armature associated withtheprofiling arm wher'eby'motion o'f'the arm causes movement of thearmature relative to the'coil.

4. Apparatus according 'to claim 1 in which themeans adapted to measurethe I independent movement of each-of the'profilin'g arms'relative tothe body includes an electrical resistance associatedwith theipro'filingarm whose'resis'tance varies with motionof the arm.

5. Apparatus according to claim 1 in which said first centering meansand said second centering means comprise shaft members extendingu-pw'ardl'y and downward1y,'-respectively, from said body memb erlongitudinally thereof, 1 'a pair oi collar members positioned aroundeach shaft member, at least one collar member on each shaft member beingarranged for limited slidable movement lengthwise of said shaft member,a first plurality of leaf spring elements circumferentially spaced aboutone of said shaft members and attached at each end to one pair of collarmembers positioned on said shaft, and a second plurality of leaf springelements circumferentially spaced about the other of said shaft membersand attached at each end to the second pair of collar members.

6. Apparatus according to claim 1 in which said orientation apparatuscomprises a magnetic compass element, a circular light mask rotatablewith said magnetic compass element and provided with a perforationhaving a fixed relation to said compass element, a second light maskfixed with respect to said body, arranged in a plane parallel to theplane of said first light mask and provided with a central aperturecapable of admitting light to said aperture in said first mask and witha reference aperture outside the area of said first mask, a light sourcemounted for rotational movement in a plane parallel to the planes ofsaid light masks, a photocell positioned on the other side of said masksfrom said light source in the path of light rays passing through saidaperture, said inclination measuring means comprising a pendulum, abeamed light source associated with said pendulum, a second photocellarranged to receive light from said light source and a third circularrotatable mask arranged between said light source and said secondphotocell, said last named mask having an aperture from the center ofthe circle to its periphery larger than a segment of the circle, andincluding means to rotate said last named mask and said orientationdevice light source in synchronism at a constant rotary speed.

7. Well logging apparatus comprising in combination a body adapted to belowered into a borehole, at least three profiling arms movably held bysaid body and equally spaced circumferentially about said body, meansurging each of said profiling arms independently outwardly from saidbody, means adapted to measure the independent movement of each of saidprofiling arms relative to said body, a first centering means and asecond centering means positioned on said body in spaced relation alongsaid body whereby said first and second centering means act to centersaid body in the borehole and to align the body with the borehole,orienting means associated with said profiling means adapted todetermine the orientation of the profiling means, and recording meansassociated with the said profiling means and the said orienting meansadapted to record the said profiles and the said orientationdeterminations.

8. Well logging apparatus comprising in combination: a body adapted tobelowered into a borehole, at least three profiling arms movably held bysaid body and equally spaced circumferentially about said body, meansurging each of said profiling arms independently outwardly from saidbody, means adapted to measure the extent of the independent movement ofeach of said profiling arms relative to said body, recording meansassociated with said profiling arms adapted to record indiciarepresentative of the extent of independent movement of each of saidarms and first and second centering means positioned on said body inspaced relation along the length of the body whereby said centeringmeans act to center said body in the borehole and to align the body withthe borehole.

FRANK G. BOUCHER.

References Cited in the file 01 this patent UNITED STATES PATENTS Number5 1,339,955 1,911,997 1,980,100 2,030,244 2,142,465 10 2,170,5272,176,169 2,190,950 2,235,533 2,267,110 15 2,281,960 2,322,343 2,322,6342,332,777 2,340,987 20 2,365,999 2,396,935 2,398,562 2,415,636 2,427,9502,444,265

Number Name Date Hardel May 11, 1920 Gillespie May 30, 1933 SchlumbergerNov. 6, 1934 Cox Feb. 11, 1936 ,Von Graf Jan. 3, 1939 Culbertson Aug.22, 1939 D011 Oct. 17, 1939 Potapenlro Feb. 20, 1940 Roberts Mar. 18,1941 Kinley Dec. 23, 1941 Vacquier May 5, 1942 Brandon June 22, 1943Howell et a1 June 22, 1943 Boucher Oct. 26, 1943 Robidoux Feb. 8, 1944Boucher Dec. 26, 1944 Walstrom Mar. 19, 1946 Russell Apr. 16, 1946Johnson Feb. 11, 1947 Dell Sept. 23, 1947 Ostheimer June 29, 1948FOREIGN PATENTS Country Date Austria 1901

